Pulled from the AH wiki, his Hero ability states:
Mythos: Before a mythos card is drawn, Tommy may cause one or more monsters that are adjacent to his location to move to his location, regardless of their normal movement.
Can Tommy use this ability to move less than every adjacent monster? For example, to pull only one Dark Young out of two that are on a location? For some reason this use of the ability never occurred to me. I always assumed he pulled every single adjacent monster